Heterogeneous transportation of alpha1B-adrenoceptor in living cells

The heterogeneous motion of alpha(1B)-adrenoceptor (alpha(1B)-AR) was visualized in living cells with BODIPY-labeled antagonist of AR by single molecule fluorescence microscopy at high spatial resolution. The moving trajectory was reconstructed by precise localization (better than 20 nm) with a least-square fit of a two-dimensional Gaussian point spread function to each single spot. Trajectory analysis revealed two apparent groups of movements: directed motion and hindered motion. The directed motion had speeds higher than 0.1 mum/s. The histogram of diffusion coefficients of the hindered motion showed distinction between the cell membrane and the cytoplasm: the diffusion coefficient was lower near the cell membrane than in the internal cytoplasm, suggesting that alpha(1B)-AR was located or trapped in different networks, which was consistent with the natural distribution of cytoskeleton in living cells. These results suggested that the heterogeneity in the motion of alpha(1B)-AR in living cell might be associated with different localizations of cell skeleton proteins in the cell, which could provide molecular insight of AR regulation in living cells.